I had to do about $8k worth of foundation repair at my last house. I'm sure the building codes differ state to state, but if you can get a couple quotes you'll start to understand the issue you face better.
I had Ram Jack come in and do a "fix everything" quote and a "minimal repair" quote. Based on experiences of other people we spoke to, we knew they would be the top tier contractor that uses all the fancy tech, which meant $$$. We used the drawings they provided in their quote to get estimates from other contractors.
Ram Jack original quote was for 22 piers, 18 outside and 4 inside, for a total of about $25k. (stay away from inside piers if you can. the quote did not include floor repair, just concrete slab repair). We found an engineer that was also a home inspector, and he gave us the info we needed to perform a true minimal repair. ended up with 9 piers outside.
The main things to ask yourself are:
are you going to be selling soon? (does it need to pass an inspection)
what is your goal to fix it? are you trying to stay ahead of a larger problem, or is this something you just noticed and are curious about?
Food for thought.